Sinclair can keep up a pretty good poker face when he needs to, but sometimes...it's really hard not to laugh. It's not that he couldn't see Jack as a fireman, it would explain a good amount of his athleticism and his affinity for thinking on his feet, but. He's relatively certain Jack just set a record for worst liar in Rapture.

But it did beg the question, what was Jack hiding?

"Not too many of those in Rapture!" he says. "How about a family? Leave anybody behind, topside?"

And only now does he take the initiative to go ahead and step in front of Jack. He's happy to follow him around, but they're never going to get to Sinclair's office that way.